The present invention relates to a non-fouling actuating mechanism, for use in aircraft stores ejector rack units and other military ordnance systems, which converts the energy output of a conventional gas combustion cartridge into piston actuated mechanical work.
Present day high performance military aircraft require external stores to be released and displaced at high velocity in order for the stores to properly leave the aircraft aerodynamic flow field. This is generally accomplished by the use of ejector racks or missile launchers and the like, which use as energy sources explosive cartridges that generate high pressure, high temperature gases. The high pressure, high temperature gases generally act on piston-actuated devices involved in bringing about ejection of the stores from the aircraft.
The burning propellants of conventional cartridges generate gases having an operating pressure of up to 18,000 psi and an operating temperature in excess of 4,500.degree. Fahrenheit. Unburned propellant, residue from ignitors, oxides from the cartridge cases and erosion of the breech all create ablative particles which will ultimately foul or jam the piping, actuating pistons, ejector guns and other components of the ejector rack system in the explosive gas train. In addition, the high pressure and temperature, alone and in conjunction with the ablative particles, will rapidly erode the actuating pistons and destroy the piston seals.
In the past, it has been necessary to remove the erosive residue by frequent periodic disassembly and cleaning of the rack and replacement of worn components. Failure to regularly perform this service affected both system operation and reliability. However, frequent disassembly, cleaning and replacement adversely affected both the cost and availability of the equipment.
Attempts have been made to circumvent the problem by developing clean burning cartridges, but with a lack of success to date.
Attempts also have been made to filter the particulates from the high pressure, high temperature gases prior to the time these particulates can act on the actuating pistons and seals. While filters have proven to be beneficial, regular disassembly and cleaning of the system components is still required. And, the finer the filtration, the more frequent the cleaning required.
Attempts also have been considered to utilize a bellows to isolate high pressure, high temperature contaminated gases from moving pistons and seals. However, these attempts have required the use of large, heavy bellows with high spring rates in order to counteract the force of the high pressure, high temperature gases; such bellows are completely inappropriate in size and weight for aircraft ejector racks and other military ordnance systems.